In April, David Marcus, Facebook Vice President of Messaging Products, watches a display showing new features of Messenger during the keynote address at the F8 Facebook Developer Conference in San Francisco.

Facebook’s Messenger app hit a record one billion users today, an impressive feat considering the world’s population is just 7.4 billion.

The news puts the iOS app among the three most popular apps of all time, along with the Facebook app itself and WhatsApp. WhatsApp, also owned by Facebook, passed the one billion users milestone in February, after seven years of existence. Messenger managed the same feat in just over four years.

“Other than Google, I’m not sure there’s another company out there that can claim a milestone like that,” Kenneth Rogerson, an associate professor at the Sanford School of Public Policy at Duke University, says in a phone interview with The Christian Science Monitor.

Ten percent of voice over IP calls (phone calls made over the internet, also provided by services like Skype and FaceTime) are made via Facebook Messenger today. Messenger has also grown as a popular way for customers to contact businesses, with about one billion business-related messages sent via the application per month, according to Venture Beat.

The app can also be used for a surprising non-communication purpose: digital sports. Messenger users can play basketball and even soccer simply by using the correct pattern of stickers and swipes. The basketball game, released during March Madness this year, has seen more than 1.2 billion plays. A similar soccer game, released just last month, has been played about 250 million times.

"If there's a pretty high percentage of people that you want to talk to that are on one platform and you don't need a phone number but you can find them by name and you can send more things and go live with audio and video, it's becoming an important communication tool for the world," David Marcus, Facebook's vice president for Messenger, told TechCrunch.

According to a Pew Research Center study published in 2015, 36 percent of online adults use messaging apps. Among younger users, between ages 18 and 29, that rises to 49 percent.

"Facebook and Google are running the show when it comes to making mobile apps that people want to download," eMarketer analyst Debra Aho Williamson told USA Today. "What they offer are apps that you want to use again and again and, quite frankly, that you need to use again and again. Very few apps can offer that."

Not all of Messenger's billion users, however, downloaded the app entirely willingly. Those who use the social media platform’s chat feature via mobile must download Messenger alongside the Facebook app. Facebook has disallowed chatting via its own mobile apps and mobile website, instead requiring users who want to chat via Facebook to download Messenger. This “forced download” has prompted complaints since 2014, despite Facebook’s assurances that the twin download policy is only to ensure the best possible customer experience.

“Since [2014], we’ve worked hard to make Messenger the best way to connect with the people you care about,” the company said in 2015, according to The Guardian, “by adding video calling, conversations with businesses, gifs and much more. [Messenger] helps messages load about 20% faster and enables richer interactions.”